The invention concerns proportional hydraulic distributors.
Such distributors are disposed between a flow generator and a receiver to control the operation of the receiver by adapting the manner in which it is connected to the flow generator.
Proportional type distributors include not only a controlled slide valve whose position determines the cross section of a flow restriction but also an automatic compensator slide valve to maintain a constant pressure differential between the upstream and downstream sides of the flow restriction so that for a given position of the control slide valve there is a given flow rate of fluid. Consequently, if a receiver is commanded by means of a proportional distributor its speed of operation is set by the position of the controlled slide valve independently of the load on the receiver.
If the flow generator is used to feed a plurality of receivers for each of which there is a proportional distributor the total flow rate demanded by the receivers may exceed the maximum flow rate that the pump is able to provide. The respective compensator slide valves are then no longer able to maintain the pressure differential between the upstream and the downstream sides of the flow restriction in each of the distributors at the predetermined constant value with the result that the most heavily loaded receivers slow down or stop while the least heavily loaded may continue to operate.